Reinforced girder

ABSTRACT

A reinforced girder including a first C-shaped member formed of sheet metal. A second C-shaped member, formed of sheet metal, is welded to the first C-shaped member to form a rectangular box. A first pair of metallic stringers is welded in a spaced-apart relationship within the first C-shaped member. The first pair of metallic stringers extends the length of the first C-shaped member. A second pair of metallic stringers is welded in a spaced-apart relationship within the second C-shaped member and extends the length of the second C-shaped member. A number of first, metallic, transverse connectors are welded in a spaced-apart relationship within the first C-shaped member between the first pair of metallic stringers. The first, metallic transverse connectors are oriented parallel to one another and at right angles to the first pair of metallic stringers. A number of second, metallic, transverse connectors are welded in a spaced-apart relationship within the second C-shaped member between the second pair of metallic stringers. The second, metallic transverse connectors are oriented parallel to one another and at right angles to the second pair of metallic stringers.

FIELD OF THE INVENTION

The present invention relates generally to static structures and, moreparticularly, to elongated rigid structures such as girders, columns,etc., having composite construction.

BACKGROUND OF THE INVENTION

Homebuilders are confronted with significant challenges in offeringhigh-quality products at competitive prices. Design trends, fluctuationsin lumber costs, and financial unrest often prevent builders fromobtaining a reasonable profit for their work. In response to marketplaceuncertainties, steel-framed home construction is becoming increasinglypopular.

Builders are attracted to the strength, termite resistance, anddimensional stability of steel. Steel materials being used in modernresidential construction are also relatively lightweight and easy tohandle. Therefore, homes with larger open spaces, longer ceiling spansand higher walls are possible.

Homes constructed with steel frames have proven to be more durable thanthose framed with wood. In areas vulnerable to hurricanes orearthquakes, they are better able to withstand forces generated by windsand shifting earth. Further, because steel is non-combustible, homesconstructed from steel easily comply with local codes and fireregulations. Because it is termite proof, pesticide treatments areunnecessary. Thus, health experts recommend steel framing for chemicallysensitive homebuyers seeking the best possible interior air quality.

Most residential steel framing is assembled using the “stick-built”construction method. Stick-built construction utilizing steel componentsis similar to that involving wood. Layout and assembly are the sameexcept for one crucial difference, steel components are joined togetherwith screws rather than nails. Powered screwdrivers make the turning ofscrews into steel framing members a snap.

SUMMARY OF THE INVENTION

It is my principal object to provide a girder that is stronger andlighter than known structural members, whether made of metal or wood, ofsimilar dimensions. My new, reinforced girder can, therefore, carrygreater loads and extend across longer spans than conventional girdersand beams. My girder, therefore, can be used in buildings with few, ifany, additional supports.

It is a further object of mine to provide a girder of the type describedthat is made of galvanized steel. Such a material is inherentlyresistant to corrosion and insect pests. It is also not combustible,making buildings constructed with my girders especially safe.

It is another object of mine to provide a girder that is easily trimmedin the field and installed in a building without resort to special toolsor the need for prolonged training. The girder is cut to a desiredlength with common tools, like reciprocating or circular saws, withmetal-cutting blades. Threaded fasteners, like self-tapping screws, areemployed to fasten the girder to another structural member. No weldingis required.

It is still a further object of mine to provide a girder that is“green,” environmentally friendly, and can be made from recycledmaterials. There are few uses for recycled wood in new buildingprojects.

I wish to provide improved features and arrangements thereof in areinforced girder for the purposes described which is lightweight inconstruction, inexpensive to manufacture, and fully dependable in use.

Briefly, my reinforced girder achieves the intended objects by featuringa pair of C-shaped channel members welded together to form a rectangularbox. A pair of stringers is welded in a spaced-apart relationship intoeach of the C-shaped channel members. The stringers extend the lengthsof the C-shaped channel members. A number of transverse connectors arewelded in a spaced-apart relationship within each of the C-shapedchannel members between the stringers. The transverse connectors areoriented parallel to one another and at right angles to the stringers toform a strong, load-bearing truss.

The foregoing and other objects, features, and advantages of myreinforced girder will become readily apparent upon further review ofthe following detailed description of the girder as illustrated in theaccompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

My invention can be more readily described with reference to theaccompanying drawings, in which:

FIG. 1 is a perspective view of a reinforced girder having portionsbroken away.

FIG. 2 is a longitudinal, cross-sectional view of the girder of FIG. 1with portions broken away.

FIG. 3 is a lateral, cross-sectional view of the girder.

Similar reference characters denote corresponding features consistentlythroughout the accompanying drawings.

DETAILED DESCRIPTION OF THE REINFORCED GIRDER

Referring now to the FIGS., a reinforced girder is shown at 10. Girder10 includes a pair of C-shaped, channel members 12 affixed to oneanother so as to form an elongated, open-ended, rectangular box.Stringers 14, affixed within the corners of the channel members 12,internally reinforce the box. Transverse connectors 16 are affixedwithin the channel members 12 and join the stringers 14 together,effectively locking stringers 14 in place.

Channel members 12 are cold-formed by bending a thin strip of galvanizedsteel sheeting into a C-shape. As shown, channel members 12 include apair of opposed end walls 18 affixed to, and extending at right anglesfrom, an intermediate wall 20. Each channel member 12 also includes apair of flanges 22 affixed to, and extending inwardly toward one anotherfrom, the free ends of end walls 18 in a common plane parallel tointermediate wall 20.

Channel members 12 are reinforced to better resist compressive,tensional, and torsional loads. In this regard, a pair of steel rods orstringers 14 is affixed, as by welding or brazing, within each of thecorners where intermediate wall 20 and end walls 18 meet. Stringers 14extend the length of members 12 which may be any desired length. At setdistances from one another, transverse connectors as at 16 are affixed,as by welding or brazing, at their ends to stringers 14 and betweentheir ends to intermediate wall 20. Connectors 16 are oriented at rightangles to stringers 14 and, together with stringers 14, form a boxtruss.

Connectors 16 are formed of the same material as stringers 14. Onesuitable type of material is rebar commonly used in reinforced concretestructures. Rebar is usually formed from carbon steel and is givenridges for better mechanical anchoring. Since rebar has an expansioncoefficient that is similar to that of channel members 12, no additionallongitudinal and perpendicular stresses develop within girder 10 atvarying temperatures during use.

Most rebar is suitable for welding and is available in different gradesthat permit a builder to pick rebar with the right strength and chemicalcomposition for a given job. Common rebar is made of unfinished,tempered steel making it susceptible to rusting. Common rebar isavailable at low cost and is usable where dry conditions are expectedthroughout the life of girder 10. Galvanized or stainless steel rebarsare, thus, employed as stringers 14 and connectors 16 in damp situationswhere corrosion of girder 10 is more likely to occur. Althoughgalvanized and stainless steel has a greater initial expense, it cangreatly increase the service life of girder 10.

After affixing stringers 14 and transverse connectors 16 within channelmembers 12, channel members 12 are affixed to one another. To do this,channel members 12 are positioned side by side with flanges 22 of onechannel member 12 in contact with the flanges 22 of the other channelmember 12. Then, channel members 12 are welded or brazed together alongthe area of contact. The step of affixing the channel members 12together requires only a few minutes to complete and leaves girder 10ready to use. Since the steps of affixing the stringers 14 andconnectors 16 in the channel members 12 similarly require only a fewminutes time, it will be appreciated that girder 10 is rapidlyconstructed.

The use of girder 10 is straightforward as it withstands loads primarilyby resisting bending forces imparted by gravity. The bending force isusually the result of the external loads and its own weight. Girder 10can also carry horizontal loads, i.e., loads due to an earthquake orwind. The loads carried by girder 10 are transferred to other girders,walls, columns, or beams, which then transfer the loads to adjacent,structural, compression members. In light frame construction, one girder10 can rest on another girder 10 and can serve as a joist, beam, orcolumn.

Internally, girder 10 experiences compressive, tensile, and shearstresses as a result of applied loads. Typically, under the influence ofgravity, the original length of girder 10 is slightly reduced to enclosea smaller radius arc at the top of girder 10, resulting in compression,while the same original length at the bottom of girder 10 is slightlystretched to enclose a larger radius arc, and so is under tension. Theoriginal length of the middle of girder 10, halfway between the top andbottom, is the same as the radial arc of bending, and so it is underneither compression nor tension.

The compressive, tensile and shear stresses generated within girder 10are shared by channel members 12, stringers 14, and connectors 16.Without stringers 14 and connectors 16, channel members 12, joined alongabutting flanges 22 to form a box, do not offer great resistance toloads. With the addition of stringers 14 and connectors 16, channelmembers 12 carry great loads and can be employed to span long distanceswithout support between their ends.

Girder 10, being hollow, is lighter in weight than its conventional,wood counterparts of similar load-bearing capability. Thus, buildingstructures, incorporating airy architectural designs, can be constructedwith relative ease and minimal cost. Transporting girder 10 to aconstruction site is relatively easy because of its lightweight. Ifgirder 10 is too long for a particular application, it can be cut tolength with conventional saws. Sheet metal screws (not shown) areemployed to secure girders 10 to other building members, such as headersand footers when used in a wall. If the sheet metal used to form channelmembers 12 is thick, it may be necessary to drill pilot holes in channelmembers 12 before the screws will penetrate.

While girder 10 has been described with a high degree of particularity,it will be appreciated by those skilled in the art that modificationscan be made to it. For example, the dimensions of channel members 12,stringers 14 and connectors 16 can be varied to accommodate expectedloads with larger features generally being more appropriate for higherloads. Furthermore, the number of connectors 16 employed betweenstringers 14 can be increased to boost the stiffness of girder 10. Alightweight girder 10 can be made by placing a single connector 16between the stringers 14 at the midpoint of each channel member 12.Finally, the diameter of rebar used in stringers 14 can be differentfrom the diameter of rebar employed in connectors 16. The respectivediameters can be selected to provide a balance of compressive, tensile,and shear stresses for a particular installation of girder 10.Therefore, it is to be understood that the present invention is notlimited to girder 10, but encompasses any and all girders within thescope of the following claims.

I claim:
 1. A reinforced girder, comprising: a first C-shaped memberbeing formed of sheet metal; a second C-shaped member being formed ofsheet metal and being welded to said first C-shaped member so as to forma rectangular box; a first pair of metallic stringers being welded in aspaced-apart relationship within said first C-shaped member, said firstpair of metallic stringers extending the length of said first C-shapedmember; a second pair of metallic stringers being welded in aspaced-apart relationship within said second C-shaped member, saidsecond pair of stringers extending the length of said second C-shapedmember; a plurality of first, metallic, transverse connectors beingwelded in a spaced-apart relationship within said first C-shaped memberbetween said first pair of metallic stringers, said first, metallictransverse connectors being oriented parallel to one another and atright angles to said first pair of metallic stringers; and, a pluralityof second, metallic, transverse connectors being welded in aspaced-apart relationship within said second C-shaped member betweensaid second pair of metallic stringers, said second, metallic transverseconnectors being oriented parallel to one another and at right angles tosaid second pair of metallic stringers.
 2. A reinforced girder,comprising: a first C-shaped member including: a first intermediatewall; a first pair of end walls being affixed to said first intermediatewall and extending at right angles therefrom; and, a first pair offlanges being affixed to said first pair of end walls and extending atright angles therefrom in a common plane parallel to said firstintermediate wall; a first pair of metallic stringers being respectivelywelded within said first C-shaped member at the junctions of said firstpair of end walls with said first intermediate wall; a plurality offirst, metallic, transverse connectors being welded in a spaced-apartrelationship to said first intermediate wall between said first pair ofmetallic stringers, said first, metallic transverse connectors beingoriented parallel to one another and at right angles to said first pairof metallic stringers; a second C-shaped member being welded to saidfirst C-shaped member so as to form a box, said second C-shaped memberincluding: a second intermediate wall; a second pair of end walls beingaffixed to said second intermediate wall and extending at right anglestherefrom; and, a second pair of flanges being affixed to said secondpair of end walls and extending at right angles therefrom in a commonplane parallel to said second intermediate wall, said second pair offlanges being in abutment with said first pair of flanges; a second pairof metallic stringers being respectively welded within said secondC-shaped member at the junctions of said second pair of end walls withsaid second intermediate wall; and, a plurality of second, metallic,transverse connectors being welded in a spaced-apart relationship tosaid second intermediate wall between said second pair of metallicstringers, said second, metallic transverse connectors being orientedparallel to one another and at right angles to said second pair ofmetallic stringers.
 3. A reinforced girder, comprising: a first C-shapedmember being formed of sheet metal; a second C-shaped member beingformed of sheet metal and being welded to said first C-shaped member soas to form a rectangular box; a first pair of metallic stringers beingwelded in a spaced-apart relationship within said first C-shaped member,said first pair of metallic stringers extending the length of said firstC-shaped member; a second pair of metallic stringers being welded in aspaced-apart relationship within said second C-shaped member, saidsecond pair of stringers extending the length of said second C-shapedmember; a first, metallic, transverse connector being welded at themidpoint of said first C-shaped member between said first pair ofmetallic stringers, said first, metallic transverse connector beingoriented at right angles to said first pair of metallic stringers; and,a second, metallic, transverse connector being welded at the midpoint ofsaid second C-shaped member between said second pair of metallicstringers, said second, metallic transverse connector being oriented atright angles to said second pair of metallic stringers.